Get the source code

Here is the screen shot when I opened the codecompletion source code in C::B's source navigator view.

Build the code completion plug-in

If you only want to build the Code Completion plug-in, you can select it in the "build target list" (Note: by default, the Build target option was "ALL", which means all the targets in the current workspace will be build), see the screen shot below:

Code completion build target option in code::blocks

Don't forget to run the batch script file "update.bat" after you build the target, this procedure will update your output folder package and strip the debug information. See the wiki page Installing_Code::Blocks_from_source_on_Windows for more information.

A brief description of every project files

From now on, we use CC as an abbreviation for code completion plug-in.

ccdebuginfo.cpp

a dialog for debugging CC, can be opened by double click on the code browser tree entry with shift and ctrl key pressed

ccoptionsdlg.cpp

code completion options dialog, can be opened by menu->setting->editor->code completion and symbols browser

ccoptionsprjdlg.cpp

setting the additional parser search path

classbrowser.cpp

viewing the symbols tree ctrl(token tree).

classbrowserbuilderthread.cpp

a thread to build the class browser tree above

codecompletion.cpp

The Main file need by code completion plug-in, maintain all the CC's GUI and native parser

insertclassmethoddlg.cpp

a dialog to insert class method, can be open by context menu in editor

nativeparser.cpp

a class derived from wxEvtHandler, NativeParser class has a member variable "Parser m_Parser";

selectincludefile.cpp

select multiply matched token names before any jump to declaration or jump to implementation.

parser/parser.cpp

Parser class was also derived from wxEvtHandler, can start batch parse... this class has member variables like :cbThreadPool m_Pool(which will create a thread from thread pool for each file need passed);TokenTree* m_pTokens(contains all the Token database);

parser/parserthread.cpp

will do the syntax analysis for every file in a project, it has a Tokenizer as member variable

parser/token.cpp

definition of the "Token" class, and TokenTree(which means the Token dababase)

parser/tokenizer.cpp

tokenizer will return every wxString it regard as a symbol by GetToken(), also do a replacement before return

parser/searchtree.cpp

implement the patricia search tree using by TokenTree

Header files

no description needed

Structure of CodeCompletion plugin

The above image show the main structure of our CodeCompletion plugins. The main class are:

CodeCompletion: this is the class for main plugin), it handle event sent from the C::B core. Toolbar handling was done in this class.

NativeParser: as a main member variable of the CodeCompletion class, this class is like the Parser manager class, it create/delete Parser instances when a project load/closed.

Parser: this class is mainly for handling Tokens. Parser class hold a TokenTree which record all the Tokens. Parser class also hold a thread pool, it can either run the parsing task in the pool(this means the parsing task will be done in a separate thread), or directly by a function call.

Parserthread: The class derived from the worker thread(cbThreadedTask class), it member function DoParse() is the function for parsing.

Besides that, when trying to show the suggestion list(auto completion list, or code completion list), the NativeParser need to analyze the current the current statement structure, and query the symbol(token) information from the Tokentree, this is mostly done in ResolveExpression() member function.

Some important note: when all Parserthread instances finish parsing job in the pool, the thread pool will send an event to its parent(in this case, it is the Parser class), so the Parser know that the parsing is done, or the Parser can assign another parsing jobs to the thread pool.

Low level parser(Lexical analysis, Tokenize)

For someone haven't heard what does "Token" and "Tokenize" mean, you should read the wikibooks article A brief explain of what does a parser do and Tokenize on wikipedia. Shortly, a Tokenizer regards your C++ or C source code as a large array of characters (sometimes, we call it a string), then this big string can be divided to small atomic strings----a token (Each token has a unique meanings and can't be divided into sub-strings. A token can be a symbol, an identifier, a keyword, a digital number, etc), meanwhile "white spaces" and "comments" were ignored by the Tokenizer.

Tokenizer class

A class named Tokenizer was implemented in "tokenizer.h" and "tokenizer.cpp". Seen from the Tokenizer's level, a token is just a unicode wxString. There are several steps to run an instance of Tokenizer.

preparing the big string

From the previous section, you know the Tokenizer is just a string cutter. So, the first step is preparing the big string. The string can either be loaded from a source file or a memory buffer. Currently, the Unicode wxString is used.(since we are all using Unicode build of code::blocks, and ANSI mode is outdated and deprecated).

Get or Peek a token

Tokenizer contains a file position indicator----m_TokenIndex(see File Open In C language) pointing to the current position of string. So, you can Get a token or Peek a token. Here is the function prototype

//Get the current token string started from m_TokenIndex, //After that, increase the m_Tokenindex
wxString GetToken();//Peak the current token string and but do *NOT* increase the m_TokenIndex
wxString PeekToken();

For example, if the Tokenizer parses the example code above, you can see how these two methods work.

After initializing the Tokenizer(preparing the big string), You firstly call the GetToken() function, which will return the first token "int" and increase the m_TokenIndex one step to "int".

Then, if you call the PeekToken(), which will return a token "main", but the tokenindex was still remaining point to "int".

If you call the GetToken() again, it will return a "main" immediately and increase the file pointer to "main".

Note: Internally, the Tokenizer class use a undo and peek cache to do the trick. Once a token is peeked, it is saved in m_Peek member, so, next time you call GetToken(), it just immediately return the cached value without calling the "DoGetToken()" procedure again.

Nested Value of braces

As you know, braces are exist in pairs, such as "{" and "}", or "[" and "]", Also, these braces can be embeded. So the Tokenizer keep a value m_NestLevel to indicate how deep you stays. If the Tokenizer meets a {, it will increase the nestValue, and if it meets a }, it will decrease the m_NestLevel. See the pseudo code in Tokenizer.cpp below:

If the Tokenizer finds that an equation sign =, it will skip any character until it meets a }, so, the class declaration or function body will be totally skipped in the unexpected way. In this case, we should manually disable this functionality by setting m_SkipUnwantedTokens = false to let the Tokenizer parse these statements correctly.

That's why you will see many situations when you enter a function, you should save the m_SkipUnwantedTokens statues and disabled it, when you leave a function, you should manually restore it.(See function implementation in ParseThread.cpp)

Return a correct token, Macro replacement

Special token should be replaced for parsing correctly. For example, in the standard c++ header (mingw), there are a string named "_GLIBCXX_STD", this should be replaced to "std". See the dialog below.

The inline function in the Tokenizer class will check whether a token should be replaced before return.

Setting the replacement mapping. Note that before return a token, a replacement map was searched to check if it matches any entry in the map, so, the bigger this map goes, the slower it will do parsing.

Note: Code Completion plug-in is not a preprocessor, so it is difficult to deal with the source mixed with many macro, or some strange macros. This is something like Ctags' replacement options "?I identifier?list" in ctags option detial or Code Completion macro FAQ

We should replace the string "_GLIBCXX_BEGIN_NESTED_NAMESPACE(std, _GLIBCXX_STD_D)"
to "namespace std {", here, we introduce two replacement rules:

_GLIBCXX_BEGIN_NESTED_NAMESPACE

+namespace

_GLIBCXX_END_NESTED_NAMESPACE

}

In this rule, we firstly replace the "_GLIBCXX_BEGIN_NESTED_NAMESPACE" with the "namespace", then, we reserve the "std", and change the closing parenthesis to an opening brace. (See the image above), also, every token string "_GLIBCXX_END_NESTED_NAMESPACE" will be replaced by "}".

AAAAA -> -BBBBB

We should replace the string "_GLIBCXX_BEGIN_NAMESPACE_TR1"
to "namespace tr1 {", here, we introduce two replacement rules:

_GLIBCXX_BEGIN_NAMESPACE_TR1

-namespace tr1 {

_GLIBCXX_END_NAMESPACE_TR1

}

In this rule, we firstly replace the "_GLIBCXX_BEGIN_NAMESPACE_TR1" with the "namespace", then, add aditional string "tr1 {"

So, the code becomes:

namespace tr1 {
...
...
}

AAAAA -> *

In this case, we call it a "strip the next "(" and ")" rule. for example:

The rule syntax is:

XXXXXX -> *

For example, In the source code below:

CVAPI(void) cvFxxxx();
CVAPI(cvMat *) cvFyyy();

will become to (if I add a replacement rule CVAPI -> *)

void cvFxxxx();
cvMat * cvFyyy();

High level parser(Syntax Analysis)

This is the main flow of a parser.

parser thread

Basically, we can say, the low level parser(Tokenizer) moves its pointer character by character, and return a wxString(token) to feed the high level parser(Syntax analyzer).All the syntax analysis was done in ParserThread. A thread must be created to parse a source file. see parserthread.cpp and parserthread.h, a thread will be allocated from thread pool. For example, a file contains these statement:

void f1();int f2(char c);float f3(void* p);int f1;double f2;

After the ParserThread finished its parsing, it will recognize five tokens, which has the keyword "f1","f2" and "f3", note, tokens can have the same names, but they differ from different types( variables, functions...).

Token class

How can a large number of tokens be recorded? A Token(note: it as a capital means it's class type) class was introduced to recorded every token. For boosting the speed of allocating Tokens, the "new" and "delete" operator were overloaded in its base class BlockAllocated. See the memory pool page on wikipedia as a reference.

You can see the Token class contains all the information needed for recording its locating, its type or class derived hierarchy...

For example, in the source code in[Low level parser(Lexical analysis)]. A Token for "main" should contains it's name (obviously , m_Name="main" ), then m_File will record which file dose this Token exist. m_Line will give the line number of "main" in this source file, and so on.

Memory Pool--BlockAllocated class

In BlockAllocated class, there is only a static member say "static BlockAllocator<T, pool_size, debug> allocator;" to keep all the pre-allocated memory for all derived class.

10000 means a pool of 10000 Tokens were allocated in the memory pool, so, dynamically allocate a Token object will be fast and efficient.

Operator new overloading for fast allocate in the heap

ParserThread

The function Parse() will do the most job of syntax analysis. See the pseudo code below.

In the DoParse(), it checks the token from Tokenizer. For example, if the token words = "enum", then, the ParserThread::HandleEnum() will do the job to parse this enum block.

A simple look ahead parser

We can explain a little about it parser, the member variable m_Str of class ParserThread will be considered as a type stack, for example, we want to parse the statement below:

symbolA symbolB symbolC symbolD;

Only symbolD can be recognized as a variable, and it has a type of "symbolA symbolB symbolC". When the parser meets each symbol, it will look ahead to see the next token is whether ";", if not, the current token will pushed to m_Str. These iteration will be ended when the parser look ahead one step from symbolD and find the next token is a ";".

DoParse Examples

Handling class declaration

The main routing of handling class was in
ParserThread::HandleClass function
If the parserThread meet these statement

class AAA{int m_a;int m_b;};

It will surely add a Token of "AAA", it's type is "class".

What about these statements

class AAA{int m_a;int m_b;} x,y,z;

The parserThread should firstly add a Token "AAA", then it should regard "x", "y", "z" are three variables of type "AAA". This was done by "ReadVarNames()" function, it will read every comma separated variables after a class declaration.

Handling typedef statement

Sometimes, you can see these code blocks:

typedefclass AAA{int m_a;int m_b;} BBB,CCC;

If the parser meets the keyword "typedef", firstly it set the "m_ParsingTypedef = ture" to indicate that we are parsing a typedef statement.

Next, it meets a keyword "class", which also indicate it is a class declaration. So, the HandleClass function will do the task. A Token of "class AAA" will be added to the TokenTree. Wait a minute, how can we deal with "BBB" and "CCC", this is not the same case as previous code, we can't regard "BBB","CCC" as variables. In this case, another function "ReadClsName()" will be called. For simplicity of TokenTree, we just regard "BBB" and "CCC" as derived class of "AAA".

How does the parserThread know between these two cases. Here is the code:

Animation of Patricia tree

A better animation demo of Patricia tree can be found in Search Tree Viewer. In this page, you can select the tree type, and enter some strings, then the tree will dynamically show in the window.

SearchTree Node

A Node should contains at least several essential element. They are:

An edge: in the image below, the gray filled area shows a Node, since each edge belong to the next node, for example, the Node has an edge "abcd".

SearchTreeItemMap: because our searchTree is a compact Patricia tree which means an edge contains many items. Such as, "ab" , "abc", "abcd" all the suffix string belong to the edge "abcd"

SearchTreeLinkMap: This is an associated container map<wxChar,NodeId>, which store all "pointers" to its child Node. In the example below, "e" points to a Node of "efg", while "x" points to "xyz".

Node depth: depth of Search Tree Node is defined by the string length from the "root node". See a depth of each node on the search tree above. For example, the Node of "hysi" has a m_Depth = 5 ("" + "p" + "hysi" = 5).

Node Lable

For example, the node "hysi" (2) has two children, they are "cs" (1) and "ology" (3), show below.

How a new item is added to the tree

When you add a new key (string) to the tree, some node should be splited, and new node need to be added. For example this postshow some details.

Suppose we have two nodes in the tree, the node id is 0 (root node) and 1, the tree hold only one key string(item) "physics":

Adding word: physics
1 items in the tree
-""(0)
\-"physics"(1)

Now, if another key string "physiology" is added to the tree, we now firstly check "physiology" is already in the tree, if not, we need to find the common string "physi", so the node 1 should be splited after the common string, so you get the following result.

Here, the middle node "physi" is added. the original node 1's lable is shorten to "cs", and a new node "ology" is added as a new child node to the middle node.

How to query a Token by a keyword

The parser collect all the Token information, and stored them in the TokenTree, the GUI function can query keywords from the database to show function tips or to build a Class Browser tree.

For example, if you want to find all the Tokens named "ab". In the picture above from TokenDatabase(TokenTree). we can search on the Patricia tree containing all the Tokens names, finaly, we find a tree node with a edge "abcd". So, "ab" is in it's Node's items list. Then, we can find a TokenIdxSet in a vector<TokenIdxSet>, this TokenIdxSet has all the index named by "ab", so, we can get the result like: There are many Tokens named "ab".Token "ab" may be a member varialbe name in a class, or a global function name...

ClassA::ab
ClassB::abvoid ab()
....

Flexible Parser structure

The Parser class( in Parser.cpp and Parser.h ) has re-factored to support every project associate with a Parser object (svn revision > 6268 ). Which means: One Parser object per project, so, every project (xxx.cbp) will hold its own Token macro defines and Token trees.

Due to the new introduced conditional preprocessor handling mechanism, the same source file may give different Tokens due to the different macro defines in different project. Also, CC support parsing on the files which does not belong to any project.

You open a project in CB, then all the files belong to the project( related to the project) will be parsed in CC.

Now, you open another file( we call it a "separate file" later) which is not belong to the current project nor any other opened project.

Then the CC will create a "temporary parser" named "NONE“ parser, and add this separate file to the "NONE" parser.

So, you can still see the class tree when viewing the separate file.

Once you close this separate file, the "NONE" parser will automatically be removed.

The main idea is: Now, We can let the CC do parse on some separate files
and support class browsing in Symbol browser.

Automatic Code Completion

Find the search scope

For example, when you are editing, and the caret position was located at "E" as shown in the above image, the first thing doing an automatic code completion is find the search scope.

Here are some steps to get the initial(first) search scope:

First, you need to correct all the "using namespace XXXX" directives at the beginning the the current source file.(labeled with "A"), this means all the child tokens of "namespace Scintilla" should be searched.

Secondly, find the function body where the current caret position locates. eg, the above code, the caret is in the "RunStyles::RunFromPosition()" function, so the function parameter variable "position"(labeled with "C" and the local variable "run" (labeled as "D") is also a matching Tokens.

Thirdly, look at the "B", this means we are in the class named "RunStyles", so, "RunStyles" is also a search scope.

Finally, don't forget the global namespace scope, because the tokens of this scope are exposed to everywhere of the source.

Break up the current statement

VariableA.m_VariableB.Functi

If you are entering the above statement, the caret is behind the "Functi". Then the whole line will be break up to several "parsing component".

There are three components: "VariableA" , "m_VariableB" and "Functi". In the next section, I will introduce that the AI matching routing will start from matching the first component with the initial(first) search scope.

Do an AI match

Doing an AI match is just like a walking on a tree, and find the final matching result.See the image below:

Here is the matching algorithm:

Now, suppose we have an initial "search scope", and a "component" array.

The AI match algorithm starts from matching the "sub search scopes" with the first "component", then, the matched "sub search scope"(red rectangle) will be the initial "search scope" again matching with the second "component", this matching routing is running continuously until we matches with the final component. Then we get the whole matching result, that will be show as a auto code completion list.

Code completion debugging support

Debug Log output

If you want to debug your plug-in, you may need to Logout the debug message to the "Code::Blocks Debug" panel. Here is the sample code:

This is a quite complex macro definition. So, if CC_CODECOMPLETION_DEBUG_OUTPUT is defined as 0, these debugging macros were disabled. If CC_CODECOMPLETION_DEBUG_OUTPUT is defined as 1, only the TRACE macro will be defined, so you can plot some messages to the Debug log. It is always the parser will parser many files, so the debug messages will be flooding. If we only interest in the debug message when we are parsing a specific source file, the best way was define CC_CODECOMPLETION_DEBUG_OUTPUT as 2. Now, TRACE macro will plot the message only in one source file. The source file name can be specified in token.cpp

const wxString g_DebugTraceFile = _T("myfile.cpp");

This way, only the debug message when parsing "myfile.cpp" will be traced.

Code-Completion debug tool dialog

When you press shift and ctrl key and double click on any entry of the navigator tree entry, a debug tool dialog will pop up to give a more detail about the selected token. You can query its information such as its member variables, its Ancestors and so on.

Debug Smart Sense log output

When you hold theshift and ctrl key and right click on any entry of the navigator tree entry, the context menu will have a "Debug SmartSense" menu entry shown. You can click it to enable it. See the image blow. Then, all the debug log information when doing an Auto-completion will be shown in the "Debug Log" panel.

Mutexs and lockers in CC

We need lockers to avoid multiply thread issues of wxString. More detailed can be found: wxString and the locker issue in our CC code, to avoid such issue, we need lockers.
There are three main kind of lockers.
wxMutex s_ParserMutex;
wxMutex s_TokenTreeMutex;
wxMutex m_ClassBrowserBuilderThreadMutex;
The first one was to protect multiply access to Parser objects, this is a static variable. The second one tries to forbid the multiply access to the TokenTree, the last one is used to build the symbol browser tree(usually show in the left docked panels of the C::B main frame)